Fresh Grapes and Health – Research Highlights
Grapes beneficially impact the cardiovascular system in a number of ways, as demonstrated in numerous cell, animal and human studies on table Grapes, grape juice and wine. Grapes are a source of highly effective antioxidants that are absorbed and used by the body – they are bioactive and they improve antioxidant status in the human body.
Polyphenols are perhaps the most well known of the grape antioxidant families: flavonoids and resveratrol are different types of polyphenols found in Grapes. Many of the following studies were conducted using regular table Grapes (a blend of green, red and black Grapes) that were provided in powdered form to ensure the scientific validity of the studies.
Importantly, consuming modest amounts of Grapes / Grape Juice have shown beneficial effects. Grape consumption significantly improves blood vessel function and antioxidant capacity of blood.
A pilot human study showed that eating a modest amount of a variety of Grapes (about 1 1/4 cups) had immediate favorable effects on blood vessel function in 5 normal, healthy, male subjects, and that regular intake of Grapes at that amount, but twice a day, caused even greater improvements in blood vessel function and antioxidant capacity. [Bauer, JA, Vascular Pharmacology, 2009]
Grapes increase antioxidant capacity in humans to offset the damaging effects of post-meal oxidative stress.
- Human subjects consuming Grapes with a high fat meal completely prevented the damaging impact (a 50% reduction in blood flow) that was observed with a high fat meal consumed without Grapes. [Bauer, JA, Vascular Pharmacology, 2009]
- In another human study, grape consumption dramatically increased blood antioxidant capacity and prevented post-meal oxidative stress, a natural state of oxidative stress in the body that results from eating a meal containing just protein, carbohydrates and fat, with no antioxidants. [Prior, RL, Journal American College of Nutrition, 2006]
Eating Grapes reduced risk factors for heart disease and reduced oxidative stress
- Pre- and post-menopausal women consuming 1 1/4 cups of Grapes per day saw the reduction of key risk factors for coronary heart disease. These included a reduction in blood triglyceride levels, LDL cholesterol levels, and key markers for inflammation in the body. Additionally, the researchers observed a significant reduction in whole body oxidative stress. [Fernandez, ML, Journal of Nutrition, 2005]
- A laboratory study showed that adding Grapes to the diet of rats prevented the accumulation of harmful oxidized cholesterol as well as the development of atherosclerotic lesions grape-enriched diet. Specifically, the grape-enriched diet reduced oxidative stress, increased serum antioxidant capacity, reduced cell uptake of oxidized LDL cholesterol and decreased the oxidation of LDL in general. These processes eventually reduce the accumulation of cholesterol in the cells and inhibit atherosclerosis. [Fuhrman, B., Journal of Nutrition, 2005]
Grapes lowered blood pressure, improved heart function, reduced inflammation and reduced heart muscle damage
- In a recent laboratory study, grape consumption protected against high blood pressure and the development of heart failure commonly associated with a high-salt diet. Specifically, the study examined the impact of adding Grapes to the diet of lab rats consuming either a high- or low-salt diet and also those receiving a mild dose of a common blood pressure drug, hydrazine. Those consuming a grape-enriched diet had lower blood pressure, better heart function, reduced inflammation throughout their bodies, and fewer signs of heart muscle damage than those consuming the same diet but without Grapes. Additionally, while the group receiving the blood pressure medicine also had lower blood pressure, their hearts were not protected from damage as they were in the grape-fed group. [Bolling, SF, Seymour, EM, Journal Gerontology, 2008]
Grapes Against Cancer
- Grape consumption may help protect normal colon tissue in humans by inhibiting a biochemical pathway involved in initiating colon cancer cell growth. In a pilot human study of colon cancer patients, researchers studied the effects of consuming regular table Grapes (a blend of red, green and black Grapes in powdered form) on colon tissue. After the subjects consumed Grapes for two weeks, samples of healthy and cancerous tissue were taken from each subject’s colon. The results showed a 47% reduction in the expression of the target genes responsible for promoting tumor growth in the colon, compared to baseline measurements before the study. Interestingly, the greatest effects were seen with the lowest intake of Grapes tested, which was just 2 1/2 cups per day. Additionally, the beneficial effects were seen in the healthy tissue of the cancer patients, but not the cancerous tissue, suggesting that regular consumption of Grapes may be potentially beneficial to maintaining a healthy colon. [Holcombe, RF, presented at Society for Integrative Oncology, 2007]
- Grape constituents have consistently demonstrated anti-cancer attributes in laboratory cell and animal studies, through a wide variety of mechanisms. While breast cancer and leukemia are leading areas of study, numerous studies using human cells have been conducted related to other cancer sites including the colon, prostate, stomach, skin and more.
- Resveratrol has been shown to have inhibitory effects at all three stages of carcinogenesis (initiation, promotion and progression) in mouse skin cancer models as well as in various murine models of human cancers [Athar et. al., 2007].
- Increased grape consumption has been linked to a reduced risk of oral cancer. [Zheng, et al. 1993]
- Intake of resveratrol from Grapes has been associated with a reduced risk of breast cancer, but not with resveratrol obtained from wine. [Levi, et al. 2005]
Grapes and Brain Health
Grapes or grape constituents may help protect brain health by offsetting oxidative stress and inflammation, or by targeting the actions of certain genes involved in diseases of the brain, such as Alzheimer’s and Parkinson’s Disease as shown in preliminary laboratory studies.
- A study of aging mice that were either consuming a diet with or without Grapes, found that the grape-enriched diet was able to dramatically increase the expression of critical target genes that block the Alzheimer’s pathway and decrease inflammation in the brain. [Klein, et al. presented at Society for Neuroscience Annual Meeting, 2007]
- Resveratrol has been shown to block the actions of beta amyloid peptide, a key protein that promotes the development of Alzheimer’s. [Savaskan, et. al, 2003; Marambaud et al, 2005]
- Resveratrol and other antioxidants protected Parkinson’s-like nerve cells against oxidative damage. [Frankel D and Schipper HM, 1999]
Grapes and Arthritis
Grapes decreased pain associated with arthritis and enhanced the impact of anti-inflammatory medicine in animal study
Using an animal model of arthritis, four different treatments in rats were studied: sugar water (control); Grapes (in powder form); the commonly used non-steroidal anti-inflammatory drug meloxicam; and a combined treatment with Grapes and meloxicam.
The grape-enriched diet significantly reduced the amount of pain related to the arthritis, while the drug showed no impact on pain.
Interestingly, the combination treatment of Grapes and meloxicam gave greater pain relief than either did on its own. [Raja, et al., Society of Neuroscience Meeting, 2008]
Urinary Tract Health
Grapes shown to protect against the loss of bladder function typically associated with an enlarged prostate
A series of animal studies investigated the impact of adding Grapes (in powder form); to the diet on bladder function. The most recent study showed that Grapes prevented and delayed the damaging effects of ischemia (oxygen deprivation) and free radicals in the presence of a partial obstruction to the bladder. This work extends earlier studies that showed a strong antioxidant effect and membrane-protective properties of Grapes that significantly reduced and reversed bladder damage caused by a partial outlet obstruction. The beneficial effects were attributed to the combination of multiple active components in Grapes — not just one. [Levin R, 2005]